EP3383586A1

EP3383586A1 - Spring assembly to position liners in a blast wheel machine

Info

Publication number: EP3383586A1
Application number: EP15804472.7A
Authority: EP
Inventors: Stepan KAPSA
Original assignee: Wheelabrator Group Ltd
Current assignee: Wheelabrator Group Ltd
Priority date: 2015-12-02
Filing date: 2015-12-02
Publication date: 2018-10-10
Also published as: WO2017092806A1

Abstract

A spring assembly (80) positions a liner (56) with respect to a housing (12) of a centrifugal blast wheel machine (10). The spring assembly (80) is mounted on a front wall (50) of the housing (12) and configured to exert a spring force against the liner (56) to push the end liner (56) against side wall liners (58, 62). The spring assembly (80) includes a spring base plate (82) attached to the front wall (50) of the housing (12), at least one spring (92) configured to engage the spring base plate (82), a spring bracket (104) configured to secure the spring (92) in place with respect to the spring base plate (82), and at least one fastener (84) to secure the spring bracket (104) to the spring base plate (82). The spring (92) is disposed between the spring base plate (82) and the spring bracket (104).

Description

SPRING ASSEMBLY TO POSITION LINERS IN A BLAST WHEEL MACHINE

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates generally to abrasive blast wheels and methods for cleaning or treating surfaces of work pieces, and more particularly to a spring assembly that is used to position a liner within a centrifugal blast wheel machine.

2. Discussion of Related Art

Centrifugal blast wheel machines generally include a rotatable wheel having a plate or a pair of spaced plates that carry radially extending blades. Particulate matter is discharged from a center of the blast wheel onto rotating surfaces of the blades, which propel the particulate matter against surfaces of a work piece to be cleaned or treated. Specifically, blast media is fed from a feed spout into a rotating impeller situated within a control cage at the center of the blast wheel. The media is fed from the impeller, though an opening in the control cage, and onto the heels or the inner ends of the rotating blades. The media travels along the faces of the blades and is thrown from the tips of the blades at the work piece surfaces to be treated.

Current centrifugal blast wheels offer some form of replaceable wear protection from the continuous erosion of blast media accelerated through the rotatable hub of the blast wheel. This replaceable protection includes a variety of materials (alloys) in the form of casted alloy plates placed in strategic areas within the wheel housing. Replacing existing liner materials is costly and difficult to perform. Specifically, with prior methods of securing liners in the blast wheel machine, the liners are fixed in place by threaded fasteners. Abrasive enters the threads of the fasteners, which need to be cleaned prior dismantling and re-installing the liners. During dismantling and re-installing the liners, the threaded parts of the fasteners can be damaged by the abrasive and must be fixed or replaced, which leads to longer down time of blast wheel machine. SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to a centrifugal blast wheel machine comprising a housing, a wheel assembly coupled to the housing, the wheel assembly including a plurality of blades configured to throw blast media introduced into the wheel assembly against a work piece, an impeller positioned about an axis of the wheel assembly, the impeller having a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller, a control cage surrounding the impeller and having a cage media outlet adapted for passage of blast media, a motor coupled to the impeller to drive the rotation of the impeller and the wheel assembly, a liner configured to be secured to the housing, and a spring assembly to position the liner with respect to the housing. In one embodiment, the spring assembly is mounted on a front wall of the housing and configured to exert a spring force against the liner to push the end liner against side wall liners.

Embodiments of the centrifugal blast wheel machine further may include the spring assembly having a spring base plate attached to the front wall of the housing, at least one spring configured to engage the spring base plate, and a spring bracket configured to secure the at least one spring in place with respect to the spring base plate. The spring base plate may include a generally V-shaped middle portion and two foot portions provided at the ends of the V-shaped middle portion. The spring assembly further may include at least one fastener to secure the spring bracket to the spring base plate, with the at least one spring being disposed between the spring base plate and the spring bracket. The V-shaped middle portion may be positioned adjacent to the at least one fastener. The foot portions of the spring base plate may extend from the V-shaped middle portion in such a manner that the foot portions engage the front wall of the housing in a generally perpendicular direction. The at least one spring may include a generally V-shaped middle portion and two foot portions provided at the ends of the V- shaped middle portion. A bottom of the "V" of the V-shaped middle portion of the at least one spring may be positioned within a bottom of the "V" of the V-shaped middle portion of the spring base plate. The foot portions of the at least one spring may extend from the V-shaped middle portion in such a manner that the foot portions engage the front wall of the housing in a generally perpendicular direction. The at least one spring may include engagement surfaces provided between the V-shaped middle portion and the foot portions, respectively, the engagement surfaces being positioned to engage the liner to position the liner in place. The spring bracket may include a body having several fingers provided at one end of the body and several fingers provided at an opposite end of the body. The fingers at the one end of the body may define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein. The fingers at the opposite end of the body may define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein. The at least one spring may be held in place by positioning the at least one spring within the spring base plate and positioning the spring bracket over the at least one spring so that the at least one spring is received in the slots. The liner may include a side that faces an interior of the housing, an opposite side that faces the front wall of the housing, and two opposite ends that face respective side walls of the housing. One end of the liner may include a stepped end profile that mates with a stepped end profile of an end of a side wall liner and the other end of the liner includes a stepped end profile that mates with a stepped end profile of an end of the other side wall liner.

Another aspect of the present disclosure is directed to a spring assembly to position a liner with respect to a housing of a centrifugal blast wheel machine, the spring assembly to position the liner with respect to the housing, the spring assembly being mounted on a front wall of the housing and configured to exert a spring force against the liner to push the end liner against side wall liners. In one embodiment, the spring assembly comprises a spring base plate attached to the front wall of the housing, at least one spring configured to engage the spring base plate, a spring bracket configured to secure the at least one spring in place with respect to the spring base plate, and at least one fastener to secure the spring bracket to the spring base plate, with the at least one spring being disposed between the spring base plate and the spring bracket.

Embodiments of the spring assembly further may include the spring base plate having a generally V-shaped middle portion and two foot portions provided at the ends of the V-shaped middle portion. The at least one spring may include a generally V-shaped middle portion and two foot portions provided at the ends of the V-shaped middle portion. A bottom of the "V" of the V-shaped middle portion of the at least one spring may be positioned within a bottom of the "V" of the V-shaped middle portion of the spring base plate. The at least one spring may include engagement surfaces provided between the V-shaped middle portion and the foot portions, respectively, the engagement surfaces being positioned to engage the liner to position the liner in place. The spring bracket may include a body having several fingers provided at one end of the body and several fingers provided at an opposite end of the body. The fingers at the one end of the body may define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein. The fingers at the opposite end of the body may define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. 1 is a perspective view of a portion of a centrifugal blast wheel machine;

FIG. 2 is another perspective view of the centrifugal blast wheel machine;

FIG. 3 is an exploded perspective view of the centrifugal blast wheel machine;

FIG. 4 is a perspective view of a feed spout of the centrifugal blast wheel machine;

FIG. 5 is a cross-sectional view of the centrifugal blast wheel machine;

FIG. 6 is an enlarged cross-sectional view of a portion of a housing of the centrifugal blast wheel machine;

FIG. 7 is a perspective view of a spring assembly of an embodiment of the present disclosure used to position a liner to the housing of the centrifugal blast wheel machine;

FIG. 8 is a side view of the spring assembly shown in FIG. 7;

FIG. 9 is an exploded perspective view of the spring assembly;

FIG. 10 is a side view of a spring assembly of another embodiment of the present disclosure; and FIG. 11 is a side view of a spring assembly of yet another embodiment of the present disclosure.

DETAILED DESCRIPTION

The blast wheel of embodiments of the present disclosure is designed to throw metallic shot, grit, cut wire, etc., which together may be referred to as "abrasive," "abrasive blast media," "abrasive media," "blast media," "media" or any suitable description of particulate matter. The blast wheel machine typically consists of four primary components that act in conjunction to throw the media at a target object to be cleaned, peened or otherwise have its surface prepared. An impeller acts to accelerate the abrasive media once the media is fed into a wheel assembly. The impeller rotates within the interior of a control cage, which may also be referred to as an "impeller case." The control cage acts to meter the abrasive blast media flow through an opening formed in the control cage to direct the flow of media onto rotating blades by adjusting the position of the opening. The control cage is stationary within the blast wheel under operating conditions. The blades (generally from two to twelve in number) rotate outside of the control cage and propel the abrasive blast media along their radial length toward the target. A bare wheel, which may also be referred to as a "runner head" or simply as a "wheel" or "blast wheel," holds the impeller and blades, and typically rotates the impeller and blades between 1500-3600 revolutions per minute (rpm) by way of a power source, which in one embodiment is an electric motor.

Embodiments of the present disclosure are directed to positioning and securing liners (also known wear plates) in the blast wheel to eliminate the use of threaded fasteners previously used to fix the liners in place. The majority of liners used within the blast wheel industry use threaded fasteners. When replacing the liners, the abrasive blast media can enter the threads, thereby blocking access to the threads and causing damage to the threads. When using a spring assembly of embodiments of the present disclosure to fix the liners in place, it has been shown that the liners can be dismantled, re-installed and held in place without the risk of abrasive entering the threaded fasteners.

Referring to the drawings, and more particularly to FIGS. 1-4, a centrifugal blast wheel machine is generally indicated at 10. In one embodiment, the centrifugal blast wheel machine 10 includes a housing, generally indicated at 12, which is designed to house the components of the centrifugal blast wheel machine. The centrifugal blast wheel machine 10 further includes a rotating impeller 14 supported by a drive shaft, a control cage assembly, generally indicated at 16, which surrounds the impeller, and a blast wheel assembly, generally indicated at 18, which receives the control cage assembly. A motor 20 is provided to drive the rotation of the impeller 14 and the blast wheel assembly 18. The arrangement is such that blast media is fed from a feed spout 22 into the rotating impeller 14, which is driven by the motor 20. By contact with vanes of the rotating impeller 14 (as well as with other particles of media already in the impeller), blast media particles are accelerated, giving rise to a centrifugal force that moves the particles in radial direction, away from the axis of the impeller. The blast media particles, now moving in a generally circular direction as well as outwards, move through openings formed in the impeller 14 into a space between the impeller and a control cage of the control cage assembly 16, still being carried by the movement of the impeller vanes (also known as impellor dams) and the other particles.

When the blast media particles that have passed though the impeller openings into the space between the impeller 14 and the control cage assembly 16 reach an opening provided in the control cage assembly, rotational and centrifugal forces move the particles through the opening and onto ends of the vanes. The control cage assembly 16 functions to meter a consistent and appropriate amount of blast media onto the blades of the blast wheel assembly 18. As the vanes of the impeller 14 rotate, the blast media particles are moved along their lengths and accelerate until they reach the ends of the vanes and thrown from the ends of the vanes. Although the impeller 14 is shown to be cylindrical in shape, the size and thickness of the impeller may vary depending on the size of a blast wheel assembly and the desired performance characteristics. For example, the impeller 14 may have interior or exterior walls that taper in either direction along its axis. Typically, the impeller will be made of a ferrous material, such as cast or machined iron or steel, although other materials may also be appropriate. In one particular embodiment, the impeller is formed of cast white iron.

The blast wheel assembly 18 of the centrifugal blast wheel machine 10 includes a hub or wheel 24 and a plurality of blades, each indicated at 26, to throw blast media introduced into the wheel assembly to treat the work piece contained within the housing 12. The arrangement is such that the impeller 14 is positioned about an axis of the wheel 24 of the blast wheel assembly 18, with the impeller having a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller. The control cage of the control cage assembly 16 surrounds the impeller 14 in a position in which the media outlet of the control cage assembly is adapted for passage of blast media to the heel ends of the blades of the blast wheel assembly 18. As mentioned above, the motor 20 is coupled to the impeller 14 and to the blast wheel assembly 18 to drive the rotation of the impeller and the wheel assembly.

The control cage assembly 16 for the abrasive blast wheel assembly 18 is configured to lock a control cage of the control cage assembly in place. In one embodiment, the control cage assembly 16 of the present disclosure includes a control cage 28 having a cylindrical wall 30 forming a housing defining an interior chamber and a media outlet or opening 32 formed in the cylindrical wall for allowing the egress of blast media from the interior chamber. A typical centrifugal blast wheel machine 10 having the control cage 28 is used to treat a surface (not shown) of a work piece by projecting blast media (not shown) at the surface. The treatment may be in the nature of cleaning, peening, abrading, eroding, de -burring, de-flashing, and the like, and the blast media typically consists of solid particles such as shot, grit, segments of wire, sodium bicarbonate, or other abrasives, depending on the surface being treated and/or the material being removed from the surface.

The control cage 28 of the control cage assembly 16, typically formed of cast iron (or similar material), is positioned concentrically around impeller 14 and, is

approximately cylindrical in shape. Like the impeller 14, however, the control cage 28 may have other shapes, and may, for example, taper internally and/or externally in either direction along its axis. The control cage 28 also includes an outer flange or locking ring 34, which mates with an adaptor plate 36, which in turn is mounted on the wheel 24 of the blast wheel assembly 18, fixing the control cage with respect to the wheel and preventing the control cage from rotating with respect to the wheel upon operation of the blast wheel assembly 10. A retaining ring 38 is further provided to firmly secure the locking ring 34 and to prevent the rotational movement of the control cage 28 with respect to the adaptor plate 36 after securing the adaptor plate to the blast wheel 24 of the blast wheel assembly 18. The control cage 28 is then locked in place by placing the feed spout 22 onto the control cage and by firmly securing a feed spout bracket 40.

In other embodiments, the control cage 28 may be restrained from movement by attachment to other stationary elements of the blast wheel assembly 18 or its environment (as indicated above), or, in some cases, may be allowed to or made to rotate in one or both directions. As shown, one of two retaining rings 38 may be provided, with one of the retaining rings having markings or other indicia that allow a user to position the control cage 28 in a certain desired rotational orientation, so as to control the direction of the media being thrown by the blast wheel assembly 18.

As mentioned above, the media opening 32 of the control cage 28 allows egress of blast media upon operation of the blast wheel assembly 18. In the illustrated embodiment, the media opening 32 is approximately rectangular in shape when viewed from the side (i.e., in a direction perpendicular to its axis) and is approximately 3/5 the height of the cylindrical wall 30 of the control cage 28. The size, shape, and location of the media opening 32 may vary depending on the application, however. The length of the media opening 32 is measured in degrees, from the innermost portion of the opening furthest ahead in the direction of rotation to the outermost edge of the trailing portion. While the media opening 32 of the shown embodiment is approximately seventy degrees for a wheel rotating in either direction, in other embodiments, the length of the opening (in either direction) may vaiy, depending numerous factors such as the overall size of the blast wheel assembly 18, the nature of the media being thrown, and the desired rate of flow, as would be understood by one of skill in the art.

The blast wheel assembly 18, which is arranged concentrically around control cage 28, includes the plurality of blades 26 sandwiched between a rear wheel and a front wheel of the wheel 24 of the wheel assembly. The various parts of blast wheel assembly 18 are typically formed of cast iron, although they may also be made of any other appropriate material and/or method. The blast wheel assembly 18 is connected to the motor 20, in this embodiment by means of key inserted to lock a shaft of motor to the rear wheel of the wheel assembly, so that wheel assembly may be rotated by motor during operation of the blast wheel assembly. Blades 26, each of which have a heel end and a tip, are constructed and arranged to direct the blast media at the surface being treated. The blades 26 may be of any suitable size and any suitable shape, including one or more of straight, curved, flared, flat, concave, or convex shapes.

In one embodiment, the blades 26 may embody semi-curved blades, each blade having a curved portion positioned adjacent a central hub of the wheel assembly 18, and a straight portion integrally formed with the curved portion extending radially outwardly from the wheel assembly.

Referring to FIG. 5, the housing 12 of the centrifugal blast wheel machine 10 includes a circumferential or front wall 50, which surrounds the impeller 14, the control cage assembly 16 and the blast wheel assembly 18. The housing 12 further includes side walls, 52, 54 (FIG. 3), which enclose the sides of the housing. The arrangement is such that the front wall 50 and the side walls 52, 54 of the housing 12 enclose the components of the centrifugal blast wheel machine 10 to contain blast media within the housing. As shown, the housing 12 further includes several end liners, each indicated at 56, which are secured and positioned with respect to the end wall 50 of the housing in the manner set forth below. Specifically, in one embodiment, there are three end liners 56 provided along the surface of the end wall 50; however, any number of end liners may be provided. In one embodiment, the end liners 56 of the centrifugal blast wheel machine 10 function to guide abrasive media propelled by the blades 26 out of an optimal blast pattern into an interior of the housing 12. The end liners 56 are stationary within the housing 12 of the centrifugal blast wheel machine 10.

Referring to FIG. 6, the manner in which the end liners 56 are secured to the housing 12 of the centrifugal blast wheel machine 10 will be described. As shown, the side wall 52 includes a side wall liner 58 that is suitably secured to the side wall 52. The side wall liner 58 includes a stepped end profile 60 provided at the end of the side wall liner. Similarly, the other side wall 54 includes a side wall liner 62 that is secured to the side wall 54. The side wall liner 62 includes a stepped end profile 64 provided at the end of the side wall liner. The stepped end profiles 60, 64 of the side wall liners 58, 62, respectively, together create a slot 66 that is configured to receive and retain the end liner 56 in a certain orientation with respect to the housing 12. Specifically, the end liner 56 includes a side 68 that faces the interior of the housing 12 of the centrifugal blast wheel machine 10, an opposite side 70 that faces the front wall 50 of the housing, and two opposite ends 72, 74 that face respective side walls 52, 54 of the housing. The end 72 of the end liner 56 includes a stepped end profile 76 that mates with the stepped end profile 60 of the side wall liner 58. Similarly, the other end 74 of the end liner 56 includes a stepped end profile 78 that mates with the stepped end profile 64 of the other side wall liner 62. The arrangement is such that the end liner 56 fits within the space 66 defined by the stepped end profiles 60, 64 of the side wall liners 58, 62. The stepped end profiles 76, 78 of the end liner 56 and the stepped end profiles 60, 64 of the side wall liners 58, 62 mesh or otherwise interlock with one another to form a labyrinth to contain the abrasive media within the housing 12 of the centrifugal blast wheel machine 10.

As shown in FIGS. 5 and 6, the end liners 56 that are positioned along straight sections of the front wall 50 are fixed in place by two spring assemblies, each generally indicated at 80. The spring assembly 80 is mounted on the front wall 50 of the housing 12 and configured to exert a spring force against the end liner 56 to push the end liner against the stepped end profiles 60, 64 of the side wall liners 58, 62 thereby causing the stepped end profiles 76, 78 of the end liner 56 against the stepped end profiles of the side wall liners. It should be understood that more than one spring assembly 80 can be employed to fix each end liner 56 in place. The spring assembly 80 is designed to enable a tool-free removal and installation of the end liner 56 to reduce downtime during maintenance.

Referring to FIGS. 7-9, and more particularly to FIG. 9, the spring assembly 80 includes a spring base plate 82 that is attached to the front wall 50 by two screw fasteners, each indicated at 84. As shown, the spring base plate 82 includes a generally V-shaped middle portion 86 and two foot portions 88, 90 provided at the ends of the V- shaped middle portion. The screw fasteners 84 are secured to the front wall 50 of the housing 12, e.g., by screwing the screw fasteners within tapped openings provided in the front wall, with the V-shaped middle portion 86 of the spring base plate 82 disposed between the screw fasteners. As shown, the bottom of the "V" of the V-shaped middle portion 86 of the spring base plate 82 is positioned adjacent to the screw fasteners. The foot portions 88, 90 of the spring base plate 82 extend from the V-shaped middle portion 86 in such a manner that the foot portions engage the front wall 50 of the housing 12 in a generally perpendicular direction.

The spring assembly 80 further includes two springs, each indicated at 92, configured to engage the spring base plate 82. The springs 92 provide a spring force against the liner 56 during use. Although two springs 92 are shown and described as part of spring assembly 80, the spring assembly 80 may include a single spring or more than two springs to provide the spring force against the liner 56. Each spring 92 includes a generally V-shaped middle portion 94 and two foot portions 96, 98 provided at the ends of the V-shaped middle portion. As shown, the bottom of the "V" of the V-shaped middle portion 94 of each spring 92 is positioned within the bottom of the "V" of the V- shaped middle portion 86 of the spring base plate 82. The foot portions 96, 98 of each spring 92 extend from the V-shaped middle portion 94 in such a manner that the foot portions engage the front wall 50 of the housing 12 in a generally perpendicular direction. Each spring further includes engagement surfaces 100, 102 provided between the V- shaped middle portion 94 and the foot portions 96, 98, respectively. The engagement surfaces 100, 102 are positioned to engage the end liner 56 to position the end liner against the side wall liners 58, 62.

To secure the springs 92 in place with respect to the spring base plate 82, the spring assembly 80 further includes a spring bracket 104. As shown, the spring bracket 104 includes a body 106 having two openings 108, 1 10, each opening being sized to receive the screw fasteners 84 therein. The body 106 of the spring bracket 104 further includes several fingers provided at one end 1 12 of the body and several fingers provided at an opposite end 1 14 of the body. The fingers at the one end 1 12 of the body 106 define two slots, each indicated at 1 16, with each slot being sized to receive the V-shaped middle portions 94 of the springs 92 therein. Similarly, the fingers at the opposite end 1 14 of the body 106 define two slots, each indicated at 1 18, with each slot being sized to receive the V-shaped middle portions 94 of the springs 92 therein. The arrangement is such that the springs 92 are held in place by positioning the springs 92 within the spring base plate 82 and positioning the spring bracket 104 over the springs so that the springs are received in the slots 116, 1 18 and the openings 108, 1 10 receive the screw fasteners 84. The components of the spring assembly 80 are held in place by two nuts, each indicated at 120, with the aid of two washers, each indicated at 122.

Once assembled, the engagement surfaces 102 of the springs 92 of the spring assemblies 80 apply a spring force against the end liners 56 to ensure that the end liners are held in place against the side wall liners 58, 62. The end liners 56 are removed by sliding the end liners out of the slot 66.

FIG. 10 illustrates a spring assembly, generally indicated at 200, of another embodiment of the present disclosure that is designed to position the end liner 56 with respect to the front wall 50 of the housing 12. The spring assembly 200 includes a spring made of spring steel sheet that is pushed into a grove in a pin and held in place by the force of the spring.

FIG. 11 illustrates another spring assembly, generally indicated at 300, of yet another embodiment of the present disclosure that is designed to position the end liner 56 with respect to the front wall 50 of the housing 12. The spring assembly 300 includes a spring made of spring steel wire that is pushed into a grove in a pin and held in place by the force of the spring.

With spring assemblies 200 and 300, the springs associated with these assemblies are fixed to a front wall using the special shapes of the springs, without having to use a base plate, a bracket, and fasteners.

It should be observed that the spring assembly of embodiments of the present disclosure enables a smoother and tool- free dismantling and re-installation of the liners to reduce down time of the blast wheel during maintenance. The spring assembly further enables the dismantling and re-installing of the liners without need of any tooling, resulting in a shorter blast wheel downtime and higher shot blast machine availability. The spring assembly further enables shock absorbing function of the spring arrangement in situations in which there are larger impact forces against the liner, e.g., when bigger particles are propelled by blades against the liner. By providing a smoother dismantling and re-installation of the liners, shorter maintenance times for the centrifugal blast wheel machine may be achieved, thereby resulting in higher availability of the centrifugal blast wheel machine. Liners are often replaced wear parts within a centrifugal blast wheel machine, so the shorter down time of the blast wheel translates into higher shot blast machine availability. This results in higher blast capacity of the machine for the operator.

Embodiments of the spring assemblies of the present disclosure are envisioned for use on any of the centrifugal blast wheel machine designs used within the industry, regardless of liner shape. The design of the spring assembly in relation to the liner and blast wheel housing is not limited to the sketches and design found optimal in testing for this example.

Having thus described several aspects of at least one embodiment of this disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the disclosure. Accordingly, the foregoing description and drawings are by way of example only.

It will be appreciated that the features of the dependent claims that follow can be used in combination in any number, and in any combination, with any of the independent claims. We hereby disclose all combinations of dependent claims, in any number, and any combination, with any of the independent claims.

What is claimed is:

Claims

1. A centrifugal blast wheel machine comprising:

a housing;

a wheel assembly coupled to the housing, the wheel assembly including a plurality of blades configured to throw blast media introduced into the wheel assembly against a work piece;

an impeller positioned about an axis of the wheel assembly, the impeller having a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller;

a control cage surrounding the impeller and having a cage media outlet adapted for passage of blast media;

a motor coupled to the impeller to drive the rotation of the impeller and the wheel assembly;

a liner configured to be secured to the housing; and

a spring assembly to position the liner with respect to the housing, the spring assembly being mounted on a front wall of the housing and configured to exert a spring force against the liner to push the end liner against side wall liners.

2. The centrifugal blast wheel machine of claim 1, wherein the spring assembly includes a spring base plate attached to the front wall of the housing, at least one spring configured to engage the spring base plate, and a spring bracket configured to secure the at least one spring in place with respect to the spring base plate.

3. The centrifugal blast wheel machine of claim 2, wherein the spring base plate includes a generally V-shaped middle portion and two foot portions provided at the ends of the V-shaped middle portion.

4. The centrifugal blast wheel machine of claim 3, wherein spring assembly further includes at least one fastener to secure the spring bracket to the spring base plate, with the at least one spring being disposed between the spring base plate and the spring bracket.

5. The centrifugal blast wheel machine of claim 4, wherein the V-shaped middle portion is positioned adjacent to the at least one fastener.

6. The centrifugal blast wheel machine of claim 3, wherein the foot portions of the spring base plate extend from the V-shaped middle portion in such a manner that the foot portions engage the front wall of the housing in a generally perpendicular direction.

7. The centrifugal blast wheel machine of claim 3, wherein the at least one spring includes a generally V-shaped middle portion and two foot portions provided at the ends of the V-shaped middle portion.

8. The centrifugal blast wheel machine of claim 7, wherein a bottom of the "V" of the V-shaped middle portion of the at least one spring is positioned within a bottom of the "V" of the V-shaped middle portion of the spring base plate.

9. The centrifugal blast wheel machine of claim 8, wherein the foot portions of the at least one spring extends from the V-shaped middle portion in such a manner that the foot portions engage the front wall of the housing in a generally perpendicular direction.

10. The centrifugal blast wheel machine of claim 7, wherein the at least one spring includes engagement surfaces provided between the V-shaped middle portion and the foot portions, respectively, the engagement surfaces being positioned to engage the liner to position the liner in place.

1 1. The centrifugal blast wheel machine of claim 2, wherein the spring bracket includes a body having several fingers provided at one end of the body and several fingers provided at an opposite end of the body.

12. The centrifugal blast wheel machine of claim 1 1, wherein the fingers at the one end of the body define two slots, with each slot being sized to receive the V- shaped middle portions of the at least one spring therein, and the fingers at the opposite end of the body define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein.

13. The centrifugal blast wheel machine of claim 12, wherein the at least one spring is held in place by positioning the at least one spring within the spring base plate and positioning the spring bracket over the at least one spring so that the at least one spring is received in the slots.

14. The centrifugal blast wheel machine of claim 2, wherein the liner includes a side that faces an interior of the housing, an opposite side that faces the front wall of the housing, and two opposite ends that face respective side walls of the housing.

15. The centrifugal blast wheel machine of claim 14, wherein one end of the liner includes a stepped end profile that mates with a stepped end profile of an end of a side wall liner and the other end of the liner includes a stepped end profile that mates with a stepped end profile of an end of the other side wall liner.

16. A spring assembly to position a liner with respect to a housing of a centrifugal blast wheel machine, the spring assembly being mounted on a front wall of the housing and configured to exert a spring force against the liner to push the end liner against side wall liners, the spring assembly comprising:

a spring base plate attached to the front wall of the housing;

at least one spring configured to engage the spring base plate; a spring bracket configured to secure the at least one spring in place with respect to the spring base plate; and

at least one fastener to secure the spring bracket to the spring base plate, with the at least one spring being disposed between the spring base plate and the spring bracket.

17. The spring assembly of claim 16, wherein the spring base plate includes a generally V-shaped middle portion and two foot portions provided at the ends of the V- shaped middle portion.

18. The spring assembly of claim 17, wherein the at least one spring includes a generally V-shaped middle portion and two foot portions provided at the ends of the V- shaped middle portion, and wherein a bottom of the "V" of the V-shaped middle portion of the at least one spring is positioned within a bottom of the "V" of the V-shaped middle portion of the spring base plate.

19. The spring assembly of claim 16, wherein the at least one spring includes engagement surfaces provided between the V-shaped middle portion and the foot portions, respectively, the engagement surfaces being positioned to engage the liner to position the liner in place.

20. The spring assembly of claim 16, wherein the spring bracket includes a body having several fingers provided at one end of the body and several fingers provided at an opposite end of the body, and wherein the fingers at the one end of the body define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein, and the fingers at the opposite end of the body define two slots, with each slot being sized to receive the V-shaped middle portions of the at least one spring therein.